The present disclosure relates generally to information handling systems, and more particularly to techniques for integrating selection and operation of power from battery and system power sources commonly used to provide energy to portable information handling system components such as notebook computers, personal digital assistants, cellular phones and gaming consoles.
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
A battery converts chemical energy within its material constituents into electrical energy in the process of discharging. A rechargeable battery is generally returned to its original charged state (or substantially close to it) by passing an electrical current in the opposite direction to that of the discharge. Presently well known rechargeable battery technologies include Lithium Ion (LiON), Nickel Cadmium (NiCd), and Nickel Metal Hydride (NiMH). In the past, the rechargeable batteries (also known as “dumb” batteries) provided an unpredictable source of power for the portable devices, because typically, a user of the device powered by the battery had no reliable advance warning that the energy supplied by the rechargeable battery was about to run out.
Today, through the development of “smart” or “intelligent” battery packs, batteries have become a more reliable source of power by providing information to the information handling system and eventually to a user as to the state of charge, as well as a wealth of other information. The “smart rechargeable battery”, which is well known, is typically equipped with electronic circuitry to monitor and control the operation of the battery. A smart battery system, which typically includes at least one smart battery, is operable to provide power to a portable device.
It is desirable to maximize the amount of time the portable device may be used in a battery-operated mode. Various well-known power management tools and methods of extending the time of use of batteries exist. For example, the following U.S. patents describe various aspects of using dual smart batteries and are incorporated herein by reference: Dual Smart Battery Detection System And Method For Portable Computers (U.S. Pat. No. 5,818,200), and Increased Battery Capacity Utilizing Multiple Smart Batteries (U.S. Pat. No. 6,262,562), and Smart Battery Selector Offering Power Conversion Internally Within A Portable Device (U.S. Pat. No. 5,903,764).
In U.S. Pat. No. 5,818,200, one such method of maximizing the amount of time available to a portable device operating in a battery-powered mode is disclosed. In this method, two or more batteries are included for use in a power supply for supplying energy to the portable device. In such dual battery systems, in order to limit the possibility of an over current condition it is common practice that only one of the batteries may be charged or discharged at any given time. Currently, this is accomplished by including in a dual battery system a “smart selector” component for ensuring that only the battery selected by a Basic Input Output System (BIOS) in accordance with various criteria is connected to be charged or discharged at a given time.
While smart selector circuits serve an important purpose, they suffer certain deficiencies. For example, smart selector circuits typically include several switches each including back-to-back FET's to control which battery is being charged or discharged, making it a fairly expensive circuit to implement.
In alternative power supply systems disclosed in the U.S. Pat. No. 5,818,200, the smart batteries are mutually detected by cross coupling, i.e., by directly connecting an output of one to an input of another and vice versa. While the mutual detection technique reduces the number of switches, it may not offer sufficient protection in the operation of the internal switch in case of conflicts. For example, the functionality provided by some of the removed components may not be adequately included in the improved design. More specifically, while battery A is being charged, a user may insert a new battery B, which has the internal switch in a closed position. This may result in both batteries being charged simultaneously, possibly causing an over current condition. As another example, while transitioning from charging battery A to battery B or vice versa, the user may disconnect the AC power supply. This may result in an unpredictable state of the internal switch in each battery.
Operating conflicts may arise when the controller wants to charge the battery but the battery is already fully charged or when the controller wants to charge the battery but the battery detects an over current or over temperature condition. A failure to quickly detect the removal of the AC power source may result in a system shutdown if the battery discharge switches remain in an open position. These examples illustrate that operating conflicts typically result in a reduced reliability of the power supply system.
Thus, the presence of smart batteries especially the simultaneous presence of two or more batteries in a portable device imposes certain operating constraints on the AC/smart battery power source selector circuit. Failure to impose the operating constraints may result in generating the operating conflicts, and hence in reduced reliability.
Therefore a need exists to develop techniques for integrating the selection and operation of power from battery and system power sources commonly used to provide energy to portable information handling system components. More specifically, a need exists to develop tools and techniques for reducing operating conflicts in a portable device that is less expensive and more reliable than such systems and methods heretofore available. Accordingly, it would be desirable to provide tools and techniques for integrating the selection of battery and system power sources included in an information handling system absent the disadvantages found in the prior methods discussed above.